The goal of this project is to quantify how natural behaviors modulate hemodynamic signals in the cortex, and to measure their coupling to neural activity. We will concurrently measure neural activity and hemodynamic signals, using electrophysiology, intrinsic optical signal imaging and two-photon laser scanning microscopy, in the cortex of awake, head-fixed mice. Mice will be free to alternate between running, grooming or quiescent behaviors on top of a spherical treadmill. We will use pharmacology to dissect the relative contributions of central neural and peripheral cardiovascular mechanisms in controlling cerebral blood flow. The neurovascular impulse response function, which defines the relationship between neural activity and blood flow, will be quantified across behaviors to test the constancy of neurovascular coupling. Lastly, we will test whether functional networks, areas with correlated blood flow during rest, are similarly correlated during locomotion. Understanding if, and how, the behavioral state modulates the cortical hemodynamic response, the coupling of blood flow to neural activity, and functional connectivity, are all critical for the interpretationof hemodynamic signals.